Not bad! My favorite part is the gridwork, so to speak.. I think he used those strips of sanding mesh or drywall tape for the stencil..
You are almost correct, it is just like drywall sanding mesh but it is actually a bit wider squares than that. Same concept though
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Glad you like it, it is one of my favorites!
Being a Graffiti Artist and Custom Painter myself, I notice the little details..
The colors really make the piece! The fading of red to orange to yellow, and blue fade to white, and the darker green to lighter green are what really stand out!